Use l'Hopitals?
Is that what you mean?
I don't understand this problem. Can someone please help me?
Problem:
Lim [ cos(π+Δx) +1 ] / Δx
Δx -> 0
Hint: cos(x+y)=cosx cosy-sinx siny
My attempt:
[cosπ cosΔx + sinπ sinΔx + 1]/ Δx
[-1 cosΔx + 0 sinΔx +1 ]/ Δx
(-cosΔx + 1)/ Δx
I don't know what to do from here. I want to get rid of Δx from the denominator, but I don't know how to. Can someone please help me?